Sahih al-Bukhari 3957
صحيح البخاري#3957SahihNarrated Al-Bara:The companions of (the Prophet) Muhammad who took part in Badr, told me that their number was that of Saul's (i.e. Talut's) companions who crossed the river (of Jordan) with him and they were over three-hundred-and-ten men. By Allah, none crossed the river with him but a believer. (See Qur'an 2:)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 64:9